Process for bonding polyurethane to substrate

ABSTRACT

POLYURETHANE COATINGS ARE CHEMICALLY BONDED TO SUBSTRATES, INCLUDING POLYOLEFINS AND LIKE SUBSTRATES WITH WHICH POLYURETHANES WILL NOT NORMALLY ACT, BY INCORPORATING, INTO THE POLYURETHANE COATING COMPOSITION USED TO PREPARE THE COATING, FROM 0.1 PERCENT TO 10 PERCENT BY WEIGHT, BASED ON POLYURETHANE, OF A SULFONYLAZIDE OF FORMULAE: A-(OOC-NH-C6H3(-RY)-(SO2-N3)X)M, AND 2,4,6-TRI(O=),   WHEREIN A IS THE RESIDUE OF AN ALIPHATIC ALCOHOL HAVING M HYDROXYL GROUPS AND A MOLECULAR WEIGHT LESS THAN 300, R IS LOWER-ALKOXY OR HALO, X IS 1 TO 2, Y IS 0 TO 2, AND X+Y IS $3, THE SO2N3 GROUPS ARE IN 3, 4 OR 5-POSITIONS IN THE PHENYL RINGS, PROVIDED THAT ONE SUCH POSITION IS ALWAYS UNSUBSTITUTED AND M IS 1 TO 6. THE CHEMICAL BONDING CAN BE CARRIED OUT BY IRRADIATION IMAGEWISE THEREBY MAKING THE COMPOSITIONS USEFUL IN PHOTORESIST SYSTEMS.   1,3,5-TRI(RY,(N3-SO2)X-PHENYL)-PERHYDRO-S-TRIAZINE

United States Patent O 3,752,694 PROCESS FOR BONDING POLYURETHANE TOSUBSTRATE Adrian A. R. Sayigh and Fred A. Stuber, North Haven, and HenriUlrich, North Branford, Conn., assignors to The Upjohn Company,Kalamazoo, Mich.

No Drawing. Original application Mar. 2, 1970, Ser. No. 15,948, newPatent No. 3,652,504. Divided and this application Dec. 2, 1971, Ser.No. 204,361

Int. Cl. B441! 1/50 US. Cl. 117-93.31 4 Claims ABSTRACT OF THEDISCLOSURE Polyurethane coatings are chemically bonded to substrates,including polyolefins and like substrates with which polyurethanes willnot normally react, by incorporating, into the polyurethane coatingcomposition used to prepare the coating, from 0.1 percent to 10 percentby weight, based on polyurethane, of a sulfonylazide of forwherein A isthe residue of an aliphatic alcohol having m hydroxyl groups and amolecular weight less than 300, R is lower-alkoxy or halo, 2: is l to 2,y is to 2, and x+y is j 3, the SO N groups are in 3, 4, or S-positionsin the phenyl rings, provided that one such position is alwaysunsubstituted and m is 1 to 6. The chemical bonding can be carried outby irradiation imagewise thereby making the compositions useful inphotoresist systems.

CROSS-REFERENCE TO OTHER APPLICATIONS This application is a division ofapplication Ser. No. 15,948, filed Mar. 2, 1970, and now Pat. No.3,652,504.

BACKGROUND OF THE INVENTION (1) Field of the invention This inventionrelates to novel polyurethane coating compositions and is moreparticularly directed to polyurethane coating compositions which containradiation-sensitive crosslinking agents, and with processes forchemically bonding said coating compositions to substrate.

(2) Background of the invention The preparation of polyurethane coatingsand their application as protective coatings on buildings and otherstructures subject to exposure to weathering, particularly marinestructures, and on fioors and like surfaces to render same resistant toabrasion by scuffing and the like is well-known in the art; see, forexample, Saunders and Frisch, Polyurethanes, Chemistry and Technology,Part II, pp. 453 to 468 and 477 to 485, Interscience Publishers, NewYork, 1964, and US. Pats. 3,380,950; 3,425,973; 3,428,609; 3,432,456;3,436,361; and 3,458,459.

While the use of such coatings has been highly successful in the main,there have been a number of instances in which the adhesion between thecoating and the substrate has weakened and/ or failed, particularlyafter prolonged exposure to weather or abrasive forces. This has provedto be a particular problem where the substrate is a material such as apolyolefin in which there are no free active hydrogen groups with whichany residual isocyanate groups present in the polyurethane coating wouldreact and thereby chemically bond the coating to the substrate.

We have now found that, using certain novel radiation-sensitivecrosslinking agents, it is possible to effect chemical bonding between apolyurethane coating and a substrate even when the latter is free fromactive hydrogen containing groups which would react with free isocyanate groups in said coating. Using the novel process of thisinvention, it is possible not only to improve the adhesion ofpolyurethane coatings to substrate which contain active hydrogen atomsbut also to effect chemical bonding of polyurethane coatings tosubstrates such as polyolefins and the like, which would not otherwiseenter into chemical interaction with the polyurethanes.

SUMMARY OF THE INVENTION This invention comprises a process forchemically bonding a polyurethane coating to a substrate which processcomprises:

(i) applying to said substrate a coating of a composition comprising avolatile inert organic solvent, a non-celluular polyurethane, and from0.1 percent to 10 percent by weight, based on polyurethane, of asulfonylazide selected from the class consisting of compounds of theformulae:

y and (N3 5 2) x /C& (S OzNB):

R, ogN o 0 R,

( n ah wherein A is the residue of a saturated aliphatic alcohol havingm hydroxy groups and a molecular weight less than 300, m is an integerfrom 1 to 6, R is selected from the class consisting of lower-alkyl andhalogen, x is an integer from 1 to 2, y is an integer from 0 to 2provided that the sum x+y is not greater than 3, and further providedthat m is at least 2 when x is l in Formula I, the SO N groups areattached at positions 3, 4, or 5, and R is attached in any otherwiseunsubstituted position, provided that at least one of positions 3, 4,and 5 in each benzene ring is unsubstituted; and

(ii) exposing said coated substrate to a source of radiation necessaryto activate said sulfonylazide and thereby eifect chemical bonding ofsaid polyurethane to said substrate.

The invention also comprises the coating compositions comprising apolyurethane in association with a sulfonazide as set forth above.

The term radiation-sensitive is used herein to mean that the compoundswhich it qualifies can be activated and undergo molecular modificationon exposure to thermal and/or actinic radiation.

The term lower-alkyl means alkyl from 1 to 6 carbon atoms, inclusive,such as methyl, ethyl, propyl, butyl, pentyl, hexyl and isomeric formsthereof.

The term halogen is employed in the usually accepted sense as beinginclusive of fluorine, chlorine, bromine, and iodine.

The term residue of a saturated aliphatic alcohol having in hydroxylgroups and a molecular weight less than 300" means the radical obtainedby removal of all the hydroxyl groups from an aliphatic alcohol havingthe stated number of hydroxyl groups and a molecular weight within thestated range. Examples of aliphatic alcohols meeting said specificationsare ethanol, propanol, hexanol, ethylene glycol, 1,3-propylene glycol,hexane-1,2-diol, glycerol, trimethylolethane, trimethylolpropane,hexane- 1,2,3-triol, erythritol, pentaerythritol, arabinose, glucose,arabitol and the like.

DETAILED DESCRIPTION OF THE INVENTION In preparing the polyurethanecoatings, and bonding said coatings chemically to substrates inaccordance with the invention, one can use any of the polyurethanecoating compositions already known in the art; see the summary ofreferences to typical examples of such known coatings set forth underDescription of the prior Art, supra. The novel feature of thepolyurethane coatings of the invention is that there is incorporatedinto a conventional polyurethane coating composition from about 0.1percent to about 10 percent of a sulfonylazide having the Formula I orII defined above. The incorporation can be made in any convenientmanner. For example, the sulfonazide (I) or (II), in appropriatequantity, can be added directly to the preformed polyurethane coatingcomposition. Alternatively, the sulfonazide (I) or (II) can be dissolvedin the volatile inert solvent employed as carrier in the coatingcomposition and the solution of sulfonazide can be blended into thecoating composition, or the solution of sulfonazide in solvent can beused as the carrier for the composition and the preformed polyurethanecan be dissolved therein.

It is to be noted that an upper limit has been given to the amount ofsulfonazide in the coating compositions. If sulfonazide in excess of theabove limits is used, the nitrogen which is liberated upon activation byirradiation of the sulfonazide can give rise to problems due to frothingand blowing of the polyurethane coating.

Polyurethane coating compositions, and methods for their preparation,are so well-known in the art that it is unnecessary to give a detaileddescription thereof herein. Suffice it to say that said compositions aregenerally prepared by reaction of (a) any of the extensive list ofpolyisocyanates given in the cited references with (b) an activehydrogen containing component, which can be a single component or amixture of two or more components inclusive of a wide range of polyols,polyprimary amines, and hydroxyamines such as are specificallyexemplified in the above-cited references. The reaction is generallycarried out at elevated temperatures, of the order of about 50 C. up toabout 250 C., in the presence of any of the catalysts well-known in theart for the catalysis of isocyanates and active hydrogen components.

The reaction can be carried out using a prepolymer technique or using aone-shot procedure. In the latter the components are all broughttogether and reacted substantially simultaneously. In the formerprocedure an excess of polyisocyanate is reacted with a part of thetotal amount of active hydrogen containing material and theisocyanate-terminated prepolymer is then reacted in a subsequent stepwith the remainder of the active hydrogen material. Whichever method isused the overall ratio of NCO to active hydrogen containing groupsemployed is within the range of about l.0:1.0 to about 1.05 21.0.

The polyurethane obtained as described above is then dissolved in avolatile inert solvent to form a coating composition. Alternatively, thereaction between polyisocyanate and active hydrogen containing materialcan be carried out in the presence of whatever volatile inert organicsolvent is to be used as vehicle in the subsequent application of thepolyurethane as a coating on a substrate. By inert organic solvent ismeant an organic solvent which does not. react with any of the reactantsor interfere in any other way with the desired progress of the reaction.Examples of inert organic solvents are ethyl acetate, butyl acetate,Cellosolve acetate, toluene, xylene, cyclohexanone, acetone,tetrahydrofuran, dioxane and the like. The amount of organic solventemployed is adjusted so that the amount of polyurethane present in thereaction product at the end of the reaction will be in the range ofabout 5 to about 30 percent by weight.

Accordingly, the coating compositions of the invention comprise asolution, in a volatile inert organic solvent, of a polyurethane andfrom 0.1 percent about 10 percent by weight, based on said polyurethane,of a sulfonazide of formula (I) or (II) above. Said coating compositionscan also contain conventional pigments, flowing agents, other resins andlike adjuvants commonly used in the coating art.

In applying the coating compositions to substrates any of theconventional techniques of application, such as brushing, spraying,rolling, dipping and the like can be employed. The coating so producedcan be allowed to dry and cure in air, or, alternatively, the drying andcuring step can be combined with the irradiation process required toefiect chemical bonding of the polyurethane coating to the substrate inaccordance with the invention. This is particularly so when thermalradiation is the means employed to effect said chemical bonding. Forexample, a convenient method of accomplishing simultaneously both dryingand curing of the coating and chemical bonding of the coating to thesubstrate involves exposing the coated substrate to thermal radiationfrom suitable sources such as infrared lamps, heated surfaces and thelike.

Such processes can be adapted to the production, on a continuous basis,of coated sheet or film material. For example, said film or sheetsubstrate material is first passed through a zone in which the coatingwith a polyurethane coating composition of the invention is carried outand the coated sheet or film material is subsequently passed through azone in which simultaneous drying, curing, and chemical bonding, isachieved by exposure to a source of thermal radiation.

Alternatively, the step of irradiation by a suitable source of thermalor actinic radiation can be accomplished in a separate step after thecoating has been allowed to dry and to cure. Indeed, in the case ofapplication of the polyurethanes of the invention in the form ofcoatings to exterior surfaces such as buildings, marine vessels,aircraft and the like, the step of irradiation to effect chemicalbonding of the coating to substrate can be allowed to take place usingenvironmental means such as prolonged exposure to sunlight.

A wide variety of sources of actinic radaition can be employed ineifecting bonding of the polyurethane coatings of the invention tosubstrates. Such sources include carbon arcs, mercury vapor lamps,fluorescent lamps, argon glow lamps, photographic flood lamps, andtungsten lamps. Preferably, the sources of radiation is one whichgenerates ultraviolet light of wavelength within the range of 250 nm. toabout 390 nm.

While the novel coating compositions of the invention can be used toproduce chemically bonded coatings on a wide variety of substrates, theyare particularly useful in providing chemically bonded coatings onsubstrates to which such coatings could not be bonded hitherto. Forexample, the polyurethanes of the invention can be chemically bonded tosubstrates which contain a plurality of -CH bonds. Such substrates areinclusive of polyolefins such as polyethylene, polypropylene and thelike, natural rubbers, butyl rubbers, SBR rubbers, polyisoprene,polybutadiene, polyacrylonitrile, ethylene-propylene terpolymers,copolymers of butadiene and acrylonitrile, copolymers of butadiene andmethyl methacrylate and the like. Such polymeric substrates are widelyused in the wrapping and packaging arts, particularly in the case ofclear films produced from polyethylene, polypropylene and the like. Suchfilms have proved difiicult to coat permanently with surface coatings inthe form of printing, decoration and the like. The most common method ofaccomplishing this hitherto has been by prior treatment of the film, asby exposure to corona discharge and the like, followed by application ofconventional dyestufis, printing ink and like materials.

We have now found that coating of such films can be accomplished simplyand rapidly, in a highly economical fashion, to produce a chemicallybonded coating on said film using the process described above. Ifdesired, the irradiation step of the process can be carried outimagewise. That is to say, a negative image of the printing or othermarkings to be reproduced is interposed between the coated film and thesource of either thermal or actinic radiation in the irradiation step.in this manner chemical bonding of the coating to the substrate film iseffected only in those portions of the coating which have been exposedto the radiation. The unexposed portions of the coating are thendissolved away by use of a suitable solvent, leaving on the surface ofthe substrate the desired image chemically bonded to said substrate. Thechemically bonded image so produced is extremely resistant to abrasion,exposure to solvents, oil, weather and the like, and represents a noveland efiicient manner of meeting a problem which has long been current inthe film-wrapping art.

In another, related, use of the coating compositions of the invention,the latter are employed as the components of a photoresist system. Forexample, the said polyurethanes can be used in the photographicreproduction and printing arts to produce printed masters as follows.The polyurethane is applied as a coating, in the manner described above,to an appropriate substrate such as paper, metal and the like filmsupports normally employed in the reproduction art. A negative of theimage to be repro duced, e.g. lined, screened, or half-tone negatives ordiapositives, is interposed between the supported film so obtained and asource capable of producing radiation necessary to activate thesulfonazide. The polyurethane in those portions of the supported filmexposed to the radiation is thereby bonded to the substrate. The polymerin the unexposed portions of the film can then be removed by washingwith polar solvent leaving the exposed polyurethane areas bonded to thesubstrate in the form of a positive image corresponding to the negativeused in the irradiation step. Said image has high resistance to solvent,and mechanical stresses and can be used to advantage as a master fromwhich to reproduce copies of the original.

In similar manner, photoresist systems produced from the compositions ofthe invention can be used in other photoresist applications such as inthe printing of microcircuitry and related applications which involveproduction of an image, in the form of chemically bonded polymer, on ametal substrate such as copper, followed by removal, in part or in toto,of the uncoated metal by etching. Essentially the same technique as thatdescribed above in the production of printed masters, is employed in theformation of the polyurethane image on the substrates.

The sulfonazides of Formula I which are employed in the preparation ofthe coating compositions of the invention, are readily prepared byreacting the appropriate alcohol A(OH) wherein A and m have thesignificance defined above, with at least a stoichiometric proportion,and preferably an excess, of the appropriate isocyanatobenzenesulfonylchloride of the formula:

OCN

wherein R, x and y have the significance hereinbefore defined. Thereaction is carried out under conditions wellrecognized in the art forthe condensation of hydroxyl and isocyanato groups. Advantageously, thereactants are brought together at ambient temperatures, i.e. of theorder of 20 C. to 25 C., in the presence of an inert organic solvent, ashereinbefore defined. The reaction mixture is preferably maintainedbelow about 50' C., after the reactants have been brought together, inorder to avoid reaction of the hydroxy groups in the alcohol with thesulfonyl halide moieties in the isocyanatobenzenesulfonyl chloride (HI).Such reaction would clearly give rise to undesired by-products.

If desired, the reaction between the alcohol and the sulfonyl halide(III) can be carried out in the presence of any of the catalystswell-recognized in the art as useful in promoting the reaction betweenNCO and OH groups.

The reaction of the alcohol and the sulfonyl halide (III) gives rise toan intermediate carbamate (IV) as follows:

Said carbamate (IV) can, if desired, be isolated from the reactionmixture, for example by evaporation of solvent, and purified, forexample by recrystallization, before conversion to the desiredsulfonazide (I). However, it is generally not necessary to isolate thecompound (IV) prior to its conversion to the desired sulfonazide (I).Indeed, in most instances, the reaction product obtained in the reactionof the alcohol and the sulfonylchloride (III) can be employed withoutany further treatment in the conversion to the sulfonazide (I).lllustratively, the reaction product obtained in the above process,comprising the carbamate (IV) in solution in inert organic solvent, istreated, without any purification, with the appropriate amount of sodiumazide, i.e. 1 molar proportion of sodium azide for each sulfonylchloridegroup in the carbamate (IV). The reaction with sodium azide is exothermic and is controlled, by cooling as required, to maintain thereaction temperature in the range of about 25 C. to about C. Sodiumchloride is eliminated in the reaction and precipitated from thereaction mixture thereby serving as a ready guide to the progress of thereaction.

The desired sulfonazide (I) can be separated from the reaction mixtureby conventional procedures. For example, the sodium chloride which hasprecipitated, is separated by filtration and the filtrate is evaporatedto dryness. The sulfonazide (I) so isolated can be purified, if desired,by recrystallization, chromatography or like procedures, prior to beingemployed in the preparation of the novel coating compositions of theinvention.

The isocyanatobenzenesulfonyl chlorides (III) which are employed asstarting materials in the above synthesis are, for the most part, knownin the art or can be prepared from readily available starting materials,e.g. by phosgenation of the corresponding sulfanilic acids using, forexample, the procedure described by Alberino et al., J. Polymer Science,vol. 5, PP. 3212-13, 1967.

The sulfonazides of Formula II are prepared by reacting theisocyanatobenzenesulfonyl chloride (III), directly with a substantiallystoichimetric amount of sodium azide.

The reactants are brought together, slowly, preferably in the presenceof a polar solvent such as acetonitrile, dimethylformamide and the like,to control the exothermic reaction. Cessation of deposition of sodiumchloride indicates completion of reaction. The desired sulfonazide (II)is isolated from the reaction mixture by filtering off the precipitatedsodium chloride and evaporating the filtrate to dryness. Purification ofthe residue can be achieved by recrystallization or like procedures.

The following preparations and examples describe the manner and processof making and using the invention and set forth the best modecontemplated by the inventors of carrying out the invention but are notto be construed as limiting.

PREPARATION 1 To 1.95 gms. (0.03 mole) of sodium azide in 50 ml. ofacetonitrile is added 6.5 gms. (0.03 mole) 4-isocyanatobenzenesulfonylchloride [prepared by a method described by Alberino et al. supra] in 30ml. of acetonitrile. The addition is done dropwise over a period of 12minutes with constant stirring of the mixture.

The temperature range during the addition is between 16 C. and 25 C. Asthe reaction progresses, sodium chloride precipitates from the solution,resulting in a cloudy mixture. When the addition of sulfonylchloride iscomplete, the resulting mixture is filtered to remove the sodiumchloride, and the filtrate evaporated, yielding 6.4 gms. (95.5 percenttheoretical yield) of tris(p-azidosulfonylphenyl)isocyanurate in theform of white crystals which darken between 160 C. to 170 C. and have amelting point over 300 C. The compound shows the characteristic azideabsorption at 2128 cm? and a carbonyl absorption at 1695 cm. in itsinfrared spectrum which is in agreement with the assigned structure.

Analysis.Calculated for C H N O S (percent): C, 37.50; H, 1.79. Found(percent): C, 37.55; H, 1.84.

PREPARATION 2 Using the procedure described in Preparation 1, butreplacing the 4-isocyanatobenzenesulfonyl chloride by 3-isocyanatobenzenesulfonyl chloride there is obtained tris-(m-azidosulfonylphenyl)isocyanurate.

Similarly, using the procedure described in Preparation 1, but replacing4-isocyanatobenzenesulfonyl chloride by 2-chloro 4isocyanatobenzenesulfonyl chloride, 4-isocyanato-3-methylbenzenesulfonylchloride, 2,5-dichloro-4- isocyanatobenzenesulfonyl chloride, or5-isocyanatobenzene-l,3-di(sulfonylchloride), there are obtained:

tris 3 -chloro-4-azido sulfonylphenyl iso cyanurate, tris(2-methyl-4-azido sulfonylphenyl) isocy anurate,tris(2,5-dichloro-4-azidosulfonylphenyl)isocyanurate,

and tris[3,5-di(azidosul-fonyl)phenylJisocyanurate,

respectively.

The 2-chloro-, 3-methyl-, and 2,5 dichloro 4 isocyanatobenzenesulfonylchlorides and the 5-isocyanato- 1,3-di(sulfonylchloride) employed in theabove process are obtained by phosgenation of the corresponding knownaminobenzenesulfonic acids using the procedure of Alberino, supra.

PREPARATION 3 To 3.1 gms. (0.05 mole) of ethylene glycol in 200 ml. ofacetonitrile is added a solution of 21.75 gms. (0.1 mole) ofp-iscyanat0benzenesulfonyl chloride in 50 ml. acetonitrile. The additionis accomplished over a period of about minutes with stirring and coolingat circa 3 C. to 6 C. The resulting mixture is allowed to standovernight, and then heated torefiux temperature, at which time 6.5 gms.(0.1 mole) of sodium azide is added. The mixture so obtained is heatedto 75 C. and then allowed to cool to 50 C. Sodium chloride precipitate(5.9 gms.) is filtered out. The filtrate is cooled and the solid whichseparates (5.6 gm.; melting point 168 to 172 C.) is isolated byfiltration. Water is added to the cooled filtrate,

yielding a further quantity (5.6 gms.) of White crystals which areseparated by filtration, washed and dried under vacuum. The total yieldso obtained is 11.2 gms. (45.2 percent theory) of crudeethylenebis(4-azidosulfonyl carbanilate) in the form of white crystalshaving melting point of 135 C. to 140 C. Upon recrystallization fromacetonitrile, purified product with a melting point of 165 C. to 168 C.is obtained.

Analysis-Calculated for C H N O S (percent): C, 37.65; H, 2.75. Found(percent): C, 38.45; H, 2.82.

Using the above procedure, but replacing ethylene glycol by anequivalent amount of ethanol, propyl alcohol, hexanol, or octanol, andreplacing p-isocyanatobenzenesulfonyl chloride by5-isocyanatobenzene-1,3-di(sulfonyl chloride), there are obtained ethyl,propyl, hexyl, and octyl 3,5-di(azidosulfonyl)carbanilates,respectively.

PREPARATION 4 To 2.76 gms. (0.03 mole) of glycerol in 200 ml. ofacetonitrile is added, over a period of 12 minutes, a solution of 19.57gms. (0.09 mole) of p-isocyanatobenzene sulfonyl chloride in 50 ml.acetonitrile. To the mixture is added 0.05 gms. of triethylene diamineas catalyst. The resulting mixture is heated to reflux temperature(circa C.) for about 3 hours and then 3 gms. of additionalp-isocyanatabenzenesulfonyl chloride is added. The mixture is heatedunder reflux for an additional 3 hours and then cooled to roomtemperature. To the cooled mixture is added 7.15 gms. (0.11 mole) sodiumazide and the resulting mixture is stirred for about 1 hour. Theprecipitated sodium chloride is separated by filtration. The solvent isevaporated from the filtrate and the residue triturated in concentratedhydrochloric acid. The resultant white crystals are isolated byfiltration, Washed with water and dried, yielding 21.85 gms. (96.9percent theory) of 1,2,3 propylene tris(4 azidosulfonylcarbanilate) withmelting point of to C.

Using the above procedure but replacing glycerol by an equivalent amountof erythritol, pentacrythritol, trimethylolpropane or mannitol, thereare obtained erythritol tetra(4-azidosulfonylcarbanilate),pentaerythritol terta- (4-azidosulfonylcarbanilate), trimethylolpropanetri(4- azidosulfonylcarbanilate), and mannitolhexa(4-azidosulfonylcarbanilate), respectively.

Example 1 A polyurethane made by heating a mixture of 4.95 gms. (0.005equivalent) of hydroxy-terminated polyethylene adipate (MW 1980) and0.73 gm. (0.0125 equivalent) of hexanediol with 2.19 gm. (0.0175equivalent) of diphenylmethane 4,4'-diisocyanate at about 75 C. for 5hours is dissolved in 50 ml. of tetrahydrofuran. To this solution isadded 0.2 gm. of tris(p-azidosulfonylphenyl)isocyanurate dissolved in 2ml. of acetone.

In a similar manner there are prepared polyurethane coating compositionsin which the tris(p-azidosulfonylphenyl)isocyanurate is replaced by anequal weight of ethyl p-azido sulfonylcarbanilate, glyceroltris(p-azodisulfonylcarbanilate), erythritoltetra(4-azidosulfonylcarbanilate), pentaerythritoltetra(4-azidosulfonylcarbanilate), trimethylolpropanetri(4-azidosulfonylcarbanilate), mannitol hexa(4azidosulfonylcarbanilate), tris(3-chloro-4-azidosulfonylphenyl)isocyanurate,tris(2-methyl-4-azidosulfonylphenyl)isocyanurate, and tris(2,5 dichloro4- azidosulfonylphenyl)isocyanurate.

Example 2 The coating composition of Example 1 was used to coat sheetsof polyethylene, polypropylene, nylon 66, polycetal, Mylar, using a highspeed Whirler. The coatings were exposed to the actinic radiation of amercury lamp (Hanovia type SH) for 4 minutes, the exposure plane beingat 15 cm. from the mercury arc. The exposed areas of coating were thenfound to be insoluble in tetrahydro- 9 furan and could not be rubbed 011the substrate by hard rubbing with a cloth.

In a like manner, coatings are prepared and chemically bonded to thesame substrates using any of the coating compositions described at theend of Example 1.

We claim:

1. A process for chemically bonding a polyurethane coating to asubstrate which comprises:

(i) applying to said substrate a coating of a composition comprising avolatile inert organic solvent, a non-cellular polyurethane, and from0.1 percent to 10 percent by weight, based on polyurethane, of asulfonylazide selected from the class consisting of compounds of theformulae:

wherein A is the residue of a saturated aliphatic alcohol having mhydroxy groups and a molecular 10 weight less than 300, m is an integerfrom 1 to 6, R is selected from the class consisting of lower-alkyl andhalogen, x is an integer from 1 to 2, y is an integer from to 2 providedthat the sum x+y is not greater than 3, and further provided that m isat least 2 when x is 1 in the first formula above, the SO N groups areattached at positions 3, 4, or 5, and R is attached in any otherwiseunsubstituted positions, provided that at least one of positions 3, 4,and 5 in each benzene ring is unsubstituted; and (ii) exposing saidcoated substrate to a source of radiation necessary to activate saidsulfonylazide and thereby efiect chemical bonding of said polyurethaneto said substrate. 2. The process of claim 1 wherein said sulfonylazideis ethylenebis(p-azidosulfonylcarbanilate) 3. The process of claim 1wherein said sulfonylazide is glycerol tris(p-azidosulfonylcarbanilate).

4. The process of claim 1 wherein said sulfonylazide is 20N,N,N"-tris(p-azidosulfonylphenyl)isocyanurate.

References Cited UNITED STATES PATENTS 7/1969 Laridon 96-91 N 6/1969Danh'auser et a1. 117-9331 WILLIAM D. MARTIN, Primary Examiner I. A.BELL, Assistant Examiner

